Inflatable air mattresses are most commonly used for purposes of floating in water normally for recreational purposes, although it is appreciated that they are useful in lifesaving situations, some types of recreational sports and in providing a comfortable mattress on which one may rest or sleep on dry land. If one is sunbathing on an air mattress, the person rotates from the prone to the supine position at regular intervals to provide an overall tan. Although the supine position is fairly comfortable on either land or water, the prone position can become very uncomfortable due to improper positioning of the head which is normally turned at 90.degree. to the plane of the body and hyper-extension in the lumbo-sacral region of the person's spine. There has been no attempt to alleviate this improper posture of the person particularly when lying in the prone position while in water or on land.
It has been previously thought that air mattresses are useful only as recreational devices so that the standard type of air mattress should suffice, such as disclosed in U.S. Pat. Nos. 2,068,134, 2,939,158 and 3,068,494. It is appreciated that sections of the air mattress may be hingedly connected together to convert the mattress into either a chair or lounge, such as disclosed in U.S. Pat. No. 2,623,574. U.S. Pat. No. 2,717,399 discloses an adaptation to an air mattress which facilitates under water viewing while the user is lying in the prone position on the mattress. This is achieved by the provision of a circular hole through the mattress which has a transparent bottom. This permits positioning of the user's head over the hole so that they may inspect what is on the lake or sea bottom. The hole in the mattress is normally of eight to ten inches in diameter to permit full viewing of the sea bottom. In one embodiment, the head support is provided above the viewing aperture. The head support is a cushion which contacts the forehead which can cause further elevation of the superior aspect of the head. This in turn results in hyper-extension in the cervical spine. Such posture is not nearly as comfortable as the neutral anatomical position for the head in the saggital plane.